Padding and backoff operations when transmitting via multiple frequency segments in a WLAN

ABSTRACT

A communication device determines that simultaneous transmission and reception via multiple frequency segments in a WLAN is not permitted. The communication device transmits a first packet in a first frequency segment beginning at a first time, and transmits a second packet in a second frequency segment beginning at a second time that is different than the first time. Transmission of the second packet overlaps in time with transmission of the first packet. In response to having determined that simultaneous transmission and reception via multiple frequency segments is not permitted, the communication device includes in the first packet padding so that an end of transmission of the first packet occurs at a same time as an end of transmission of the second packet.

CROSS REFERENCES TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication No. 62/863,699, entitled “Multi-Band Operation: Synchronizedand Unsynchronized,” filed on Jun. 19, 2019, which is incorporatedherein by reference in its entirety.

FIELD OF TECHNOLOGY

The present disclosure relates generally to wireless communicationsystems, and more particularly to simultaneous transmission and/orreception in multiple frequency segments in a wireless local areanetwork (WLAN).

BACKGROUND

Wireless local area networks (WLANs) have evolved rapidly over the pasttwo decades, and development of WLAN standards such as the Institute forElectrical and Electronics Engineers (IEEE) 802.11 Standard family hasimproved single-user peak data rates. One way in which data rates havebeen increased is by increasing the frequency bandwidth of communicationchannels used in WLANs. For example, the IEEE 802.11n Standard permitsaggregation of two 20 MHz sub-channels to form a 40 MHz aggregatecommunication channel, whereas the more recent IEEE 802.11ax Standardpermits aggregation of up to eight 20 MHz sub-channels to form up to 160MHz aggregate communication channels. Work has now begun on a newiteration of the IEEE 802.11 Standard, which is referred to as the IEEE802.11be Standard, or Extremely High Throughput (EHT) WLAN. The IEEE802.11be Standard may permit aggregation of as many as sixteen 20 MHzsub-channels (or perhaps even more) to form up to 320 MHz aggregatecommunication channels (or perhaps even wider aggregate communicationchannels). Additionally, the IEEE 802.11be Standard may permitaggregation of 20 MHz sub-channels in different frequency segments (forexample, separated by a gap in frequency) to form respectivecommunication links. Further, the IEEE 802.11be Standard may permitaggregation 20 MHz sub-channels in different radio frequency (RF) bandsto form a single aggregate channel, or may permit aggregation of 20 MHzsub-channels in the different RF bands to form respective communicationlinks.

The current IEEE 802.11 Standard (referred to herein as “the IEEE 802.11Standard” for simplicity) provides for a first communication device totransmit packets to a second communication device via a singlecommunication channel. The IEEE 802.11 Standard also provides mechanismsfor a device to determine whether the single communication channel isbusy or idle for purposes of determine whether the device can transmitin the single communication channel.

SUMMARY

In an embodiment, a method for simultaneously transmitting in multiplefrequency segments includes: determining, at a communication device,that simultaneous transmission and reception via multiple frequencysegments is not permitted; transmitting, by the communication device, afirst packet in a first frequency segment beginning at a first time;transmitting, by the communication device, a second packet in a secondfrequency segment beginning at a second time that is different than thefirst time, wherein transmission of the second packet overlaps in timewith transmission of the first packet; and in response to havingdetermined that simultaneous transmission and reception via multiplefrequency segments is not permitted, including in the first packetpadding so that an end of transmission of the first packet occurs at asame time as an end of transmission of the second packet.

In another embodiment, a first communication device comprises a wirelessnetwork interface device that is configured to communicate via multiplefrequency segments. The wireless network interface device includes oneor more integrated circuit (IC) devices configured to: determine thatsimultaneous transmission and reception via multiple frequency segmentsis not permitted; control the wireless network interface device totransmit a first packet in a first frequency segment beginning at afirst time; control the wireless network interface device to transmit asecond packet in a second frequency segment beginning at a second timethat is different than the first time, wherein transmission of thesecond packet overlaps in time with transmission of the first packet;and in response to having determined that simultaneous transmission andreception via multiple frequency segments is not permitted, include inthe first packet padding so that an end of transmission of the firstpacket occurs at a same time as an end of transmission of the secondpacket.

In yet another embodiment, a method for simultaneously transmitting inmultiple frequency segments includes: performing, at a communicationdevice, a backoff operation corresponding to one frequency segment amongthe multiple frequency segments, the backoff operation involvingdecrementing a backoff counter in connection with the one frequencysegment; determining, at a communication device, whether the backoffcounter of the communication device is expired; and in response todetermining that the backoff counter has expired, simultaneouslytransmitting, by the communication device, respective transmissions inrespective frequency segments beginning at a same time.

In still another embodiment, a communication device comprises a wirelessnetwork interface device that is configured to communicate via multiplefrequency segments. The wireless network interface device includes oneor more IC devices and a backoff counter implemented on the one or moreIC devices. The one or more IC devices are configured to: perform abackoff operation corresponding to one frequency segment among themultiple frequency segments, the backoff operation involvingdecrementing the backoff counter in connection with the one frequencysegment; determine whether the backoff counter is expired; and inresponse to determining that the backoff counter has expired, controlthe wireless network interface device to simultaneously transmitrespective transmissions in respective frequency segments beginning at asame time.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an example communication system in whichcommunication devices wirelessly exchange information via multiplefrequency segments, according to an embodiment.

FIG. 2A is a diagram of an example communication channel used by thecommunication system of FIG. 1 , the communication channel correspondingto multiple frequency segments, according to an embodiment.

FIG. 2B is a diagram of another example communication channel used bythe communication system of FIG. 1 , the communication channelcorresponding to multiple frequency segments, according to anotherembodiment.

FIG. 3 is a block diagram of an example wireless network interfacedevice configured to communicate via multiple frequency segments,according to an embodiment.

FIG. 4 is a diagram of an example of unsynchronized transmissions inmultiple frequency segments, according to an embodiment.

FIG. 5 is a flow diagram of an example method for simultaneouslytransmitting in multiple frequency segments, according to an embodiment.

FIG. 6 is a flow diagram of another example method for simultaneouslytransmitting in multiple frequency segments, according to an embodiment.

FIG. 7 is a diagram of an example of synchronized and simultaneoustransmissions in multiple frequency segments, according to anembodiment.

FIG. 8 is a diagram of another example of synchronized and simultaneoustransmissions in multiple frequency segments, according to anotherembodiment.

FIG. 9 is a flow diagram of another example method for simultaneouslytransmitting in multiple frequency segments, according to an embodiment.

FIG. 10 is a diagram of another example of synchronized and simultaneoustransmissions in multiple frequency segments, according to anotherembodiment.

FIG. 11 is a diagram of an example of synchronized and simultaneoustransmissions in multiple frequency segments, according to anotherembodiment.

DETAILED DESCRIPTION

A next generation wireless local area network (WLAN) protocol (e.g., theIEEE 802.11be Standard, sometimes referred to as the Extremely HighThroughput (EHT) WLAN Standard) may permit aggregation of as many assixteen (or perhaps even more) 20 MHz sub-channels to form 320 MHzaggregate communication channels (or perhaps even wider aggregatecommunication channels). Additionally, the IEEE 802.11be Standard maypermit aggregation of 20 MHz sub-channels in different frequencysegments (for example, separated by a gap in frequency) to formrespective communication links. Additionally, the IEEE 802.11be Standardmay permit the formation of multiple WLAN communication linkscorresponding to respective frequency segments. The multiple WLANcommunication links may be used to simultaneously transmit/receivedifferent information

In some embodiments described below, multiple packets are simultaneouslytransmitted in respective frequency segments beginning at differenttimes. Padding is included in one or more of the packets so thattransmission of the multiple packets end at a same time.

In some embodiments described below, respective backoff operations areperformed in connection with respective frequency segments to determinewhen simultaneous transmissions in multiple frequency segments canbegin. In other embodiments described below, a single backoff operationis performed in connection with only one frequency segment to determinewhen simultaneous transmissions in multiple frequency segments canbegin.

FIG. 1 is a diagram of an example WLAN 110 that uses multiplecommunication links in multiple frequency segments or in different radiofrequency (RF) bands, according to an embodiment. The WLAN 110 includesan access point (AP) 114 that comprises a host processor 118 coupled toa wireless network interface device 122. The wireless network interfacedevice 122 includes one or more medium access control (MAC) processors126 (sometimes referred to herein as “the MAC processor 126” forbrevity) and one or more PHY processors 130 (sometimes referred toherein as “the PHY processor 130” for brevity). The PHY processor 130includes a plurality of transceivers 134, and the transceivers 134 arecoupled to a plurality of antennas 138. Although three transceivers 134and three antennas 138 are illustrated in FIG. 1 , the AP 114 includesother suitable numbers (e.g., 1, 2, 4, 5, etc.) of transceivers 134 andantennas 138 in other embodiments. In some embodiments, the AP 114includes a higher number of antennas 138 than transceivers 134, andantenna switching techniques are utilized.

In an embodiment, the wireless network interface device 122 isconfigured for operation within a single RF band at a given time. In anembodiment, the wireless network interface device 122 is configured tosimultaneously communicate via multiple communication links inrespective frequency segments within a single RF band, and/or tocommunicate via the multiple communication links at different times. Inanother embodiment, the wireless network interface device 122 isadditionally configured for operation within two or more RF bands at thesame time or at different times. For instance, in an embodiment, thewireless network interface device 122 is configured to simultaneouslycommunicate via multiple communication links in respective RF bands,and/or to communicate via the multiple communication links at differenttimes. In an embodiment, the wireless network interface device 122includes multiple PHY processors 130, where respective PHY processors130 correspond to respective RF bands. In another embodiment, thewireless network interface device 122 includes a single PHY processor130, where each transceiver 134 includes respective RF radioscorresponding to respective RF bands.

The wireless network interface device 122 is implemented using one ormore integrated circuits (ICs) configured to operate as discussed below.For example, the MAC processor 126 may be implemented, at leastpartially, on a first IC, and the PHY processor 130 may be implemented,at least partially, on a second IC. The first IC and the second IC maybe packaged together in a single IC package thereby forming a modulardevice, or the first IC and the second IC may be coupled together on asingle printed board, for example, in various embodiments. As anotherexample, at least a portion of the MAC processor 126 and at least aportion of the PHY processor 130 may be implemented on a single IC. Forinstance, the wireless network interface device 122 may be implementedusing a system on a chip (SoC), where the SoC includes at least aportion of the MAC processor 126 and at least a portion of the PHYprocessor 130.

In an embodiment, the host processor 118 includes a processor configuredto execute machine readable instructions stored in a memory device (notshown) such as a random access memory (RAM), a read-only memory (ROM), aflash memory, etc. In an embodiment, the host processor 118 may beimplemented, at least partially, on a first IC, and the network device122 may be implemented, at least partially, on a second IC. As anotherexample, the host processor 118 and at least a portion of the wirelessnetwork interface device 122 may be implemented on a single IC.

In various embodiments, the MAC processor 126 and/or the PHY processor130 of the AP 114 are configured to generate data units, and processreceived data units, that conform to a WLAN communication protocol suchas a communication protocol conforming to the IEEE 802.11 Standard oranother suitable wireless communication protocol. For example, the MACprocessor 126 may be configured to implement MAC layer functions,including MAC layer functions of the WLAN communication protocol, andthe PHY processor 130 may be configured to implement PHY functions,including PHY functions of the WLAN communication protocol. Forinstance, the MAC processor 126 is configured to generate MAC layer dataunits such as MAC service data units (MSDUs), MAC protocol data units(MPDUs), etc., and provide the MAC layer data units to the PHY processor130. Additionally, the MAC processor 126 is configured to selectcommunication links via which MAC layer data units should be transmittedand to control the PHY processor 130 so that the MAC layer data unitsare transmitted in the selected communication links, in someembodiments. Also, the MAC processor 126 is configured to determine whenthe respective communication links are idle and available fortransmission and to control the PHY processor 130 so that MAC layer dataunits are transmitted when respective communication links are idle, insome embodiments. Additionally, the MAC processor 126 is configured todetermine when client stations are in a sleep state and thereforeunavailable to transmit or receive, in some embodiments. For example,the MAC processor 126 is configured to negotiate a schedule with aclient station for when the client station is permitted to be in thesleep state and when the client station should be in a wake state andavailable to transmit to or receive from the AP 114, according to someembodiments.

The PHY processor 130 may be configured to receive MAC layer data unitsfrom the MAC processor 126 and to encapsulate the MAC layer data unitsto generate PHY data units such as PHY protocol data units (PPDUs) fortransmission via the antennas 138. Similarly, the PHY processor 130 maybe configured to receive PHY data units that were received via theantennas 138, and to extract MAC layer data units encapsulated withinthe PHY data units. The PHY processor 130 may provide the extracted MAClayer data units to the MAC processor 126, which processes the MAC layerdata units.

PHY data units are sometimes referred to herein as “packets”, and MAClayer data units are sometimes referred to herein as “frames”.

In connection with generating one or more RF signals for transmission,the PHY processor 130 is configured to process (which may includemodulation, filtering, etc.) data corresponding to a PPDU to generateone or more digital baseband signals, and convert the digital basebandsignal(s) to one or more analog baseband signals, according to anembodiment. Additionally, the PHY processor 130 is configured toupconvert the one or more analog baseband signals to one or more RFsignals for transmission via the one or more antennas 138.

In connection with receiving one or more RF signals, the PHY processor130 is configured to downconvert the one or more RF signals to one ormore analog baseband signals, and to convert the one or more analogbaseband signals to one or more digital baseband signals. The PHYprocessor 130 is further configured to process (which may includedemodulation, filtering, etc.) the one or more digital baseband signalsto generate a PPDU.

The PHY processor 130 includes amplifiers (e.g., a low noise amplifier(LNA), a power amplifier, etc.), an RF downconverter, an RF upconverter,a plurality of filters, one or more analog-to-digital converters (ADCs),one or more digital-to-analog converters (DACs), one or more discreteFourier transform (DFT) calculators (e.g., a fast Fourier transform(FFT) calculator), one or more inverse discrete Fourier transform (IDFT)calculators (e.g., an inverse fast Fourier transform (IFFT) calculator),one or more modulators, one or more demodulators, etc., in variousembodiments.

The PHY processor 130 is configured to generate one or more RF signalsthat are provided to the one or more antennas 138. The PHY processor 130is also configured to receive one or more RF signals from the one ormore antennas 138.

The MAC processor 126 is configured to control the PHY processor 130 togenerate one or more RF signals, for example, by providing one or moreMAC layer data units (e.g., MPDUs) to the PHY processor 130, andoptionally providing one or more control signals to the PHY processor130, according to some embodiments. In an embodiment, the MAC processor126 includes a processor configured to execute machine readableinstructions stored in a memory device (not shown) such as a RAM, a ROM,a flash memory, etc. In other embodiments, the MAC processor 126additionally or alternatively includes one or more hardware statemachines.

The MAC processor 126 includes, or implements, a backoff controller 140that is configured to implement a backoff procedure in connection withdetermining when a transmission in a communication channel can proceed,according to some embodiments. The backoff controller 140 includes oneor more backoff counters (sometimes referred to as timers) 142. When thenetwork interface device 122 is to transmit and when the networkinterface device 122 determines that a transmission of a data unitfailed and is to be retransmitted, the backoff controller 140 invokesthe backoff procedure. The backoff procedure generally involves settinga backoff counter 142 and decrementing the backoff counter 142 todetermine when the network interface device 122 can transmit a frame.

The backoff counter 142 is set to a value chosen randomly orpseudo-randomly so that backoff counters of different communicationdevices in the network tend to reach zero at different times, accordingto some embodiments. While the backoff controller 140 determines that achannel medium is idle, the backoff controller 140 controls the backoffcounter 142 to decrement. On the other hand, when the backoff controller140 determines that the communication medium is busy, the backoffcontroller 140 pauses the backoff counter 142 and does not resumedecrementing the backoff counter 142 until the communication medium issubsequently determined to be idle. Generally, when the backoff counter142 reaches zero, the backoff controller 140 determines that thecommunication device is free to transmit. In some embodiments, prior totransmission, the network interface device 122 also determines whetherthe sub-channel(s) in which the transmission is to occur are idle for adetermined time period immediately prior to a start of the transmission.In some embodiments, when the backoff counter 142 reaches zero but thesub-channel(s) in which the transmission is to occur are not idle forthe determined time period immediately prior to a start of thetransmission, no transmission is made and the backoff counter is reset.

In an embodiment, determining whether the channel medium is idleincludes measuring an energy level in the channel medium and comparingthe measured energy level to a threshold. When the measured energy levelis less than the threshold, the channel medium is determined to be idle;whereas when the measured energy level meets the threshold (e.g., isgreater than the threshold, is greater than or equal to the threshold,etc.), the channel medium is determined to be busy, according to anembodiment. In some embodiments, the PHY processor 130 includes one ormore energy sensors (not shown) that measure energy levels in one ormore frequency segments of a communication channel, and the measuredenergy levels are used to determine if the channel medium is idle.

In an embodiment, setting the backoff counter 142 includes randomly orpseudorandomly choosing an initial value for the backoff counter 142from a range of initial values. In an embodiment, the range of initialvalues is [0, CW], where CW is a contention window parameter, where theinitial value and CW are in units of a slots, and where each slotcorresponds to a suitable time period. For example, the IEEE 802.11Standard defines slot times of 20 microseconds (IEEE 802.11b) and 9microseconds (IEEE 802.11a, 11n, and 11ac), where different slot timesare used for different versions of the protocol. In an embodiment, CW isinitially set to a minimum value CWmin. However, after each failedtransmission attempt (e.g., failure to receive an acknowledgment of thetransmission), the value of CW is approximately doubled with an upperbound of CWmax. The parameters CWmin and CWmax are also in units ofslots. In an embodiment, the backoff counter 142 is decremented in unitsof slots.

In some embodiments, when a communication channel comprises multiplefrequency segments, multiple respective backoff counters 142 aremaintained for the multiple frequency segments, at least in somescenarios. In some embodiments, when a communication channel comprisesmultiple frequency segments, a single backoff counter 142 is maintainedfor one of the multiple frequency segments, at least in some scenarios.

In various embodiments, the backoff controller 140 performs various actsrelated to the one or more backoff counters 142, as will be described inmore detail below, such as one or more of (or none of) i) determiningwhether to employ multiple backoff counters 142 corresponding torespective frequency segments when simultaneously transmitting viamultiple frequency segments; ii) when a single backoff counter 142 is tobe utilized when simultaneously transmitting via multiple frequencysegments, selecting one frequency segment to which the single backoffcounter 142 corresponds; etc.

In an embodiment, the backoff controller 140 is implemented by aprocessor executing machine readable instructions stored in a memory,where the machine readable instructions cause the processor to performacts described in more detail below. In another embodiment, the backoffcontroller 140 additionally or alternatively comprises hardwarecircuitry (e.g., one or more counters, one or more timers, one or morehardware state machines, etc.) that is configured to perform actsdescribed in more detail below. In some embodiments in which thehardware circuitry comprises one or more hardware state machines, theone or more hardware state machines are configured to perform actsdescribed in more detail below.

Additionally or alternatively, the MAC processor 126 includes, orimplements, a synchronized transmission controller 146 that isconfigured to determine when multiple transmissions in multiplerespective frequency segments are to be synchronized (e.g., the multipletransmissions begin at a same time, and optionally end at a same time),according to an embodiment. In some embodiments in which multiplebackoff counters 142 corresponding to respective frequency segments areemployed when simultaneously transmitting via multiple frequencysegments, the synchronized transmission controller 146 deferstransmission in all of the multiple frequency segments until all of themultiple backoff counters 142 have expired (e.g., reached zero). In someembodiments, when a simultaneous transmission via multiple frequencysegments is unsynchronized (e.g., the respective transmissions inrespective frequency segments begin at different times), thesynchronized transmission controller 146 is configured to control thePHY processor 130 so that the respective transmissions in respectivefrequency segments end at a same time.

In an embodiment, the synchronized transmission controller 146 isimplemented by a processor executing machine readable instructionsstored in a memory, where the machine readable instructions cause theprocessor to perform acts described in more detail below. In anotherembodiment, the synchronized transmission controller 146 additionally oralternatively comprises hardware circuitry that is configured to performacts described in more detail below. In some embodiments, the hardwarecircuitry comprises one or more hardware state machines that areconfigured to perform acts described in more detail below.

In other embodiments, the backoff controller 140 and/or the synchronizedtransmission controller 146 are omitted from the AP 114.

The WLAN 110 also includes a plurality of client stations 154. Althoughthree client stations 154 are illustrated in FIG. 1 , the WLAN 110includes other suitable numbers (e.g., 1, 2, 4, 5, 6, etc.) of clientstations 154 in various embodiments. The client station 154-1 includes ahost processor 158 coupled to a wireless network interface device 162.The wireless network interface device 162 includes one or more MACprocessors 166 (sometimes referred to herein as “the MAC processor 166”for brevity) and one or more PHY processors 170 (sometimes referred toherein as “the PHY processor 170” for brevity). The PHY processor 170includes a plurality of transceivers 174, and the transceivers 174 arecoupled to a plurality of antennas 178. Although three transceivers 174and three antennas 178 are illustrated in FIG. 1 , the client station154-1 includes other suitable numbers (e.g., 1, 2, 4, 5, etc.) oftransceivers 174 and antennas 178 in other embodiments. In someembodiments, the client station 154-1 includes a higher number ofantennas 178 than transceivers 174, and antenna switching techniques areutilized.

In an embodiment, the wireless network interface device 162 isconfigured for operation within a single RF band at a given time. Inanother embodiment, the wireless network interface device 162 isconfigured for operation within two or more RF bands at the same time orat different times. For example, in an embodiment, the wireless networkinterface device 162 includes multiple PHY processors 170, whererespective PHY processors 170 correspond to respective RF bands. Inanother embodiment, the wireless network interface device 162 includes asingle PHY processor 170, where each transceiver 174 includes respectiveRF radios corresponding to respective RF bands. In an embodiment, thewireless network interface device 162 includes multiple MAC processors166, where respective MAC processors 166 correspond to respective RFbands. In another embodiment, the wireless network interface device 162includes a single MAC processor 166 corresponding to the multiple RFbands.

The wireless network interface device 162 is implemented using one ormore ICs configured to operate as discussed below. For example, the MACprocessor 166 may be implemented on at least a first IC, and the PHYprocessor 170 may be implemented on at least a second IC. The first ICand the second IC may be packaged together in a single IC packagethereby forming a modular device, or the first IC and the second IC maybe coupled together on a single printed board, for example, in variousembodiments. As another example, at least a portion of the MAC processor166 and at least a portion of the PHY processor 170 may be implementedon a single IC. For instance, the wireless network interface device 162may be implemented using an SoC, where the SoC includes at least aportion of the MAC processor 166 and at least a portion of the PHYprocessor 170.

In an embodiment, the host processor 158 includes a processor configuredto execute machine readable instructions stored in a memory device (notshown) such as a RAM, a ROM, a flash memory, etc. In an embodiment, thehost processor 158 may be implemented, at least partially, on a firstIC, and the network device 162 may be implemented, at least partially,on a second IC. As another example, the host processor 158 and at leasta portion of the wireless network interface device 162 may beimplemented on a single IC.

In various embodiments, the MAC processor 166 and the PHY processor 170of the client station 154-1 are configured to generate data units, andprocess received data units, that conform to the WLAN communicationprotocol or another suitable communication protocol. For example, theMAC processor 166 may be configured to implement MAC layer functions,including MAC layer functions of the WLAN communication protocol, andthe PHY processor 170 may be configured to implement PHY functions,including PHY functions of the WLAN communication protocol. The MACprocessor 166 may be configured to generate MAC layer data units such asMSDUs, MPDUs, etc., and provide the MAC layer data units to the PHYprocessor 170. Additionally, the MAC processor 166 is configured toselect communication links via which MAC layer data units should betransmitted and to control the PHY processor 170 so that the MAC layerdata units are transmitted in the selected communication links, in someembodiments. Also, the MAC processor 166 is configured to determine whenthe respective communication links are idle and available fortransmission and to control the PHY processor 170 so that MAC layer dataunits are transmitted when respective communication links are idle, insome embodiments. Additionally, the MAC processor 166 is configured tocontrol when portions of the wireless network interface device 162 arein a sleep state or a wake state, for example to conserve power, in someembodiments. For example, the MAC processor 166 is configured tonegotiate a schedule with the AP 114 for when the client station 154-1is permitted to be in the sleep state and when the client station 154-1should be in a wake state and available to transmit to or receive fromthe AP 114, according to some embodiments.

The PHY processor 170 may be configured to receive MAC layer data unitsfrom the MAC processor 166 and encapsulate the MAC layer data units togenerate PHY data units such as PPDUs for transmission via the antennas178. Similarly, the PHY processor 170 may be configured to receive PHYdata units that were received via the antennas 178, and extract MAClayer data units encapsulated within the PHY data units. The PHYprocessor 170 may provide the extracted MAC layer data units to the MACprocessor 166, which processes the MAC layer data units.

The PHY processor 170 is configured to downconvert one or more RFsignals received via the one or more antennas 178 to one or morebaseband analog signals, and convert the analog baseband signal(s) toone or more digital baseband signals, according to an embodiment. ThePHY processor 170 is further configured to process the one or moredigital baseband signals to demodulate the one or more digital basebandsignals and to generate a PPDU. The PHY processor 170 includesamplifiers (e.g., an LNA, a power amplifier, etc.), an RF downconverter,an RF upconverter, a plurality of filters, one or more ADCs, one or moreDACs, one or more DFT calculators (e.g., an FFT calculator), one or moreIDFT calculators (e.g., an IFFT calculator), one or more modulators, oneor more demodulators, etc.

The PHY processor 170 is configured to generate one or more RF signalsthat are provided to the one or more antennas 178. The PHY processor 170is also configured to receive one or more RF signals from the one ormore antennas 178.

The MAC processor 166 is configured to control the PHY processor 170 togenerate one or more RF signals by, for example, providing one or moreMAC layer data units (e.g., MPDUs) to the PHY processor 170, andoptionally providing one or more control signals to the PHY processor170, according to some embodiments. In an embodiment, the MAC processor166 includes a processor configured to execute machine readableinstructions stored in a memory device (not shown) such as a RAM, a ROM,a flash memory, etc. In an embodiment, the MAC processor 166 includes ahardware state machine.

The MAC processor 166 includes, or implements, a backoff controller 190that is the same or similar to the backoff controller 140, according tosome embodiments. The backoff controller 190 includes one or morebackoff counters (sometimes referred to as timers) 192. While thebackoff controller 190 determines that a channel medium is idle, thebackoff controller 190 controls the backoff counter 192 to decrement. Onthe other hand, when the backoff controller 190 determines that thecommunication medium is busy, the backoff controller 190 pauses thebackoff counter 192 and does not resume decrementing the backoff counter192 until the communication medium is subsequently determined to beidle. Generally, if the communication medium is still idle when thebackoff counter 192 reaches zero, the backoff controller 190 determinesthat the communication device is free to transmit. On the other hand, ifthe communication medium is busy when the backoff counter 192 reacheszero, the backoff controller 190 resets the backoff counter 192 and theprocess repeats.

In some embodiments, when a communication channel comprises multiplefrequency segments, multiple respective backoff counters 192 aremaintained for the multiple frequency segments, at least in somescenarios. In some embodiments, when a communication channel comprisesmultiple frequency segments, a single backoff counter 192 is maintainedfor one of the multiple frequency segments, at least in some scenarios.

In various embodiments, the backoff controller 190 performs various actsrelated to the operation of one or more backoff counters 192, as will bedescribed in more detail below, such as one or more of (or none of) i)determining whether to employ multiple backoff counters 192corresponding to respective frequency segments when simultaneouslytransmitting via multiple frequency segments; ii) when a single backoffcounter 192 is to be utilized when simultaneously transmitting viamultiple frequency segments, selecting one frequency segment to whichthe single backoff counter 192 corresponds; etc.

In an embodiment, the backoff controller 190 is implemented by aprocessor executing machine readable instructions stored in a memory,where the machine readable instructions cause the processor to performacts described in more detail below. In another embodiment, the backoffcontroller 190 additionally or alternatively comprises hardwarecircuitry (e.g., one or more counters, one or more timers, one or morehardware state machines, etc.) that is configured to perform actsdescribed in more detail below. In some embodiments in which thehardware circuitry comprises one or more hardware state machines, theone or more hardware state machines are configured to perform actsdescribed in more detail below.

Additionally or alternatively, the MAC processor 166 includes, orimplements, a synchronized transmission controller 196 the same as orsimilar to the synchronized transmission controller 146, according tosome embodiments. The synchronized transmission controller 196 isconfigured to determine when multiple transmissions in multiplerespective frequency segments are to be synchronized (e.g., the multipletransmissions begin at a same time, and optionally end at a same time),according to an embodiment. In some embodiments in which multiplebackoff counters 192 corresponding to respective frequency segments areemployed when simultaneously transmitting via multiple frequencysegments, the synchronized transmission controller 196 deferstransmission in all of the multiple frequency segments until all of themultiple backoff counters 192 have expired (e.g., reached zero). In someembodiments, when a simultaneous transmission via multiple frequencysegments is unsynchronized (e.g., the respective transmissions inrespective frequency segments begin at different times), thesynchronized transmission controller 196 is configured to control thePHY processor 170 so that the respective transmissions in respectivefrequency segments end at a same time.

In an embodiment, the synchronized transmission controller 196 isimplemented by a processor executing machine readable instructionsstored in a memory, where the machine readable instructions cause theprocessor to perform acts described in more detail below. In anotherembodiment, the synchronized transmission controller 196 additionally oralternatively comprises hardware circuitry that is configured to performacts described in more detail below. In some embodiments, the hardwarecircuitry comprises one or more hardware state machines that areconfigured to perform acts described in more detail below.

In an embodiment, each of the client stations 154-2 and 154-3 has astructure that is the same as or similar to the client station 154-1. Inan embodiment, one or more of the client stations 154-2 and 154-3 has adifferent suitable structure than the client station 154-1. Each of theclient stations 154-2 and 154-3 has the same or a different number oftransceivers and antennas. For example, the client station 154-2 and/orthe client station 154-3 each have only two transceivers and twoantennas (not shown), according to an embodiment.

FIG. 2A is a diagram of an example operating channel 200 that is used inthe communication system 110 of FIG. 1 , according to an embodiment. Theoperating channel 200 comprises a plurality of subchannels 204 in afirst frequency segment 208 and a plurality of subchannels 212 in asecond frequency segment 216. The operating channel 200 spans an overallbandwidth 220. In an embodiment, the first segment 208 and the secondsegment 216 are within a same radio frequency (RF) band.

In other embodiments, the first segment 208 and the second segment 216are in different RF bands. The Federal Communication Commission (FCC)now permits wireless local area networks (WLANs) to operate in multipleRF bands, e.g., the 2.4 GHz band (approximately 2.4 to 2.5 GHz), and the5 GHz band (approximately 5.170 to 5.835 GHz). Recently, the FCCproposed that WLANs can also operate in the 6 GHz band (5.925 to 7.125GHz). Regulatory agencies in other countries/regions also permit WLANoperation in the 2.4 GHz and 5 GHz bands, and are considering permittingWLAN operation in the 6 GHz band. A future WLAN protocol, now underdevelopment, may permit multi-band operation in which a WLAN can usespectrum in multiple RF bands at the same time.

In some embodiments, the first frequency segment 208 is used as a firstcommunication link and the second frequency segment 216 is used as asecond communication link, where the first communication link and thesecond communication link are used for simultaneous transmissions.

In one embodiment, each of the subchannels 204/212 spans 20 MHz. Thus,as illustrated in FIG. 2A, the first segment 208 spans 160 MHz and thesecond segment 216 spans 80 MHz. In other embodiments, the firstfrequency segment 208 includes another suitable number of subchannels204 (e.g., one, two, four, etc.) and spans another suitable bandwidth,such as 20 MHz, 40 MHz, 80 MHz, etc., and/or the second frequencysegment 216 includes another suitable number of subchannels 212 (e.g.,one, two, eight, etc.) and spans another suitable bandwidth, such as 20MHz, 40 MHz, 160 MHz, etc.

One subchannel 204-1 in the first frequency segment 208 is designated asa primary subchannel and the other subchannels 204/212 are designated assecondary subchannels. Control and/or management frames are transmittedin the primary subchannel 204-1, according to some embodiments. In someembodiments, the primary subchannel must be idle in order for any of thesubchannels 204/212 to be used for a transmission, according to someembodiments. In some embodiments, a subchannel 212 in the secondfrequency segment 216 is also designated as a primary subchannel (notshown). In some embodiments in which the second frequency segment 216also includes a primary subchannel, control and/or management frames areadditionally or alternatively transmitted in the primary subchannel ofthe second frequency segment 216, at least in some scenarios. In otherembodiments, control and/or management frames are only transmitted inthe primary subchannel 204-1 of the first frequency segment 208.

In some embodiments in which the second frequency segment 216 alsoincludes a primary subchannel, the primary subchannel 204-1 of the firstfrequency segment 208 must be idle in order for any of the subchannels204 to be used for a transmission and the primary subchannel of thesecond frequency segment 216 must be idle in order for any of thesubchannels 212 to be used for a transmission, according to someembodiments. In other embodiments, one or more of the secondarysubchannels 204 may be used for a transmission even when the primarysubchannel 204-1 is not idle, and/or one or more of the secondarysubchannels 212 may be used for a transmission even when the primarysubchannel of the second frequency segment 216 is not idle, according tosome embodiments.

In other embodiments, no subchannel 212 in the second segment 216 isdesignated as a primary subchannel.

In an embodiment, a backoff counter 142/192 (FIG. 1 ) corresponds to aprimary subchannel of the operating channel 200, e.g., the backoffcounter 142/192 is decremented when the primary subchannel is idle andthe backoff counter 142/192 is paused when the primary subchannel isbusy. In an embodiment, a respective backoff counter 142/192 (FIG. 1 )corresponds to a respective primary subchannel of the operating channel200, e.g., the respective backoff counter 142/192 is decremented whenthe respective primary subchannel is idle and the respective backoffcounter 142/192 is paused when the respective primary subchannel isbusy.

FIG. 2B is a diagram of another example operating channel 250 that isused in the communication system 110 of FIG. 1 , according to anotherembodiment. The operating channel 250 is similar to the exampleoperating channel 200 of FIG. 2A, and like-numbered elements are notdescribed in detail for brevity. In the example operating channel 250the first frequency segment 208 and the second frequency segment 216 areseparated by a gap 254 in frequency. In some embodiments, the firstfrequency segment 208 and the second frequency segment 216 are in a sameRF band. In other embodiments, the first frequency segment 208 and thesecond frequency segment 216 are in different RF bands.

In an embodiment, a backoff counter 142/192 (FIG. 1 ) corresponds to aprimary subchannel of the operating channel 250, e.g., the backoffcounter 142/192 is decremented when the primary subchannel is idle andthe backoff counter 142/192 is paused when the primary subchannel isbusy. In an embodiment, a respective backoff counter 142/192 (FIG. 1 )corresponds to a respective primary subchannel of the operating channel250, e.g., the respective backoff counter 142/192 is decremented whenthe respective primary subchannel is idle and the respective backoffcounter 142/192 is paused when the respective primary subchannel isbusy.

Referring now to FIGS. 2A and 2B, one or more of the subchannels 204/212are “punctured” (not shown in FIGS. 2A and 2B, e.g., nothing istransmitted within the “punctured” subchannels, according to someembodiments.

Although the example operating channels 200 and 250 of FIGS. 2A-B areillustrated as including two frequency segments 208/216, other suitableoperating channels include three or more frequency segments (e.g.,include a third frequency segment, include a third frequency segment anda fourth frequency segment, etc.). In some embodiments, a thirdfrequency segment is separated from the second frequency segment 216 bya gap in frequency in which nothing is transmitted, similar to the gap254. In some embodiments, a third frequency segment is contiguous infrequency with the second frequency segment 216.

In some embodiments, respective frequency segments such as illustratedin FIGS. 2A-B are associated with different MAC addresses. For example,in embodiments in which the respective frequency segments are uses asrespective communication links, the respective communication linkscorrespond to different MAC addresses.

FIG. 3 is a diagram of an example network interface device 300configured for simultaneous communication via multiple communicationlinks in respective frequency segments, according to an embodiment. Thenetwork interface device 300 is an embodiment of the network interfacedevice 122 of the AP 114 of Fig. The network interface device 300 is anembodiment the network interface device 162 of the client station 154-1of FIG. 1 . In other embodiments, the network interface device 122and/or the network interface device 162 have a different suitablestructure than the network interface device 300. Additionally, in someembodiments, the network interface device 300 is used in anothersuitable communication device than the communication devices of FIG. 1 ,and/or is used in another suitable wireless network than the wirelessnetwork of FIG. 1

The network interface device 300 is configured for simultaneouscommunication via a first communication link in a first frequencysegment and a second communication link in a second frequency segment,in the illustrated embodiment.

The network interface device 300 includes a MAC processor 304 coupled toa PHY processors 308. The MAC processor 304 exchanges frames (or PSDUs)with the PHY processors 308.

In an embodiment, the MAC processor 304 corresponds to the MAC processor126 of FIG. 1 . In another embodiment, the MAC processor 304 correspondsto the MAC processor 166 of FIG. 1 . In an embodiment, the PHYprocessors 308 corresponds to the one or more PHY processors 130 of FIG.1 . In another embodiment, the PHY processors 308 corresponds to the oneor more PHY processors 170 of FIG. 1 .

The MAC processor 304 includes common MAC logic 312 and link specific(LS) MAC logic 316. The common MAC logic 312 generally implements MAClayer functions that are common to the multiple communication links. Forinstance, the common MAC logic 312 is configured to, in response toreceiving data (e.g., from a host processor (not shown), from a wiredcommunication link (not shown), etc.) that is to be forwarded to anothercommunication device in the WLAN, encapsulate the data in MAC layer dataunits such as MSDUs, MPDUs, aggregate MPDUs (A-MPDUs), etc., fortransmission via the multiple communication links and to decapsulatedata from MSDUs, MPDUs, A-MPDUs, etc., that were received via themultiple communication links. Additionally, the common MAC logic 312 isconfigured to select communication links via which MAC layer data unitsshould be transmitted, in some embodiments.

Each LS MAC logic 316 generally implements MAC layer functions that arespecific to the particular communication link to which the LS MAC logic316 corresponds. For example, the LS MAC logic 316 a is configured todetermine when the first communication link is idle and available fortransmission, and the LS MAC logic 316 b is configured to determine whenthe second communication link is idle and available for transmission, insome embodiments. In some embodiments, each LS MAC logic 316 isassociated with a respective network address (e.g., a MAC address),i.e., the LS MAC logic 316 a is associated with a first network address(e.g., a first MAC address) and the LS MAC logic 316 a is associatedwith a second network address (e.g., a second MAC address) that isdifferent than the first network address.

In some embodiments, the common MAC logic 312 implements the backoffcontroller 140/190 discussed above with reference to FIG. 1 . In someembodiments, the common MAC logic 312 additionally or alternativelyimplements the synchronized transmission controller 196 discussed abovewith reference to FIG. 1 . In some embodiments, some or all of thebackoff controller 140/190 is implemented as respective link specificbackoff controllers 140/190 in respective LS MAC logic 316.

The PHY processor 308 a includes a baseband signal processor 320 acorresponding to the first communication link, and the PHY processor 308b includes a baseband signal processor 320 b corresponding to the secondcommunication link. The PHY processor 308 a also includes a first RFradio (Radio-1) 328 a corresponding to the first communication link, andthe PHY processor 308 b includes a second RF radio (Radio-2) 328 bcorresponding to the second communication link. The baseband signalprocessor 320 a is coupled to the first RF radio 328 a and the basebandsignal processor 320 b is coupled to the second RF radio 328 b. In anembodiment, the RF radio 328 a and the RF radio 328 b correspond to thetransceivers 134 of FIG. 1 . In another embodiment, the RF radio 328 aand the RF radio 328 b correspond to the transceivers 174 of FIG. 1 . Inan embodiment, the RF radio 328 a is configured to operate on a first RFband, and the RF radio 328 b is configured to operate on a second RFband. In another embodiment, the RF radio 328 a and the RF radio 328 bare both configured to operate on the same RF band.

In an embodiment, the baseband signal processors 320 are configured toreceive frames (or PSDUs) from the MAC processor 304, and encapsulatethe frames (or PSDUs) into respective packets and generate respectivebaseband signals corresponding to the respective packets.

The baseband signal processor 320 a provides the respective basebandsignal generated by the baseband signal processor 320 a to the Radio-1328 a. The baseband signal processor 320 b provides the respectivebaseband signal generated by the baseband signal processor 320 b to theRadio-1 328 b. The Radio-1 328 a and Radio-2 328 b upconvert therespective baseband signals to generate respective RF signals fortransmission via the first communication link and the secondcommunication link, respectively. The Radio-1 328 a transmits a first RFsignal via the first frequency segment and the Radio-2 328 b transmits asecond RF signal via the second frequency segment.

The Radio-1 328 a and the Radio-2 328 b are also configured to receiverespective RF signals via the first communication link and the secondcommunication link, respectively. The Radio-1 328 a and the Radio-2 328b generate respective baseband signals corresponding to the respectivereceived signals. The generated respective baseband signals are providedto the respective baseband signal processors 320 a and 320 b. Therespective baseband signal processors 320 a and 320 b generaterespective PSDUs corresponding to the respective received signals, andprovide the respective PSDUs to the MAC processor 304. The MAC processor304 processes the PSDUs received from the baseband signal processors 320a and 320 b, in an embodiment.

In some embodiments, the common MAC logic 312 and/or the LS MAC logic316 are implemented, at least partially, by a processor configured toexecute machine readable instructions stored in a memory device (notshown) such as a RAM, a ROM, a flash memory, etc. In other embodiments,the common MAC logic 312 and/or the LS MAC logic 316 are implemented,additionally or alternatively, by hardware logic such as one or morehardware state machines.

In some embodiments, the baseband signal processors 320 are implemented,at least partially, by a processor configured to execute machinereadable instructions stored in a memory device (not shown) such as aRAM, a ROM, a flash memory, etc. In other embodiments, the basebandsignal processors 320 are implemented, additionally or alternatively, byhardware logic such as one or more hardware state machines, hardwarecalculators (e.g., FFT calculators, IFFT calculators), hardwaremodulators, etc.

Although the example network interface 300 illustrated in FIG. 3includes a single MAC processor 304, other suitable network interfacedevices include multiple MAC processors, with respective ones of themultiple MAC processors 304 corresponding to respective ones of thecommunication links, in some embodiments. Although the example networkinterface 300 illustrated in FIG. 3 includes multiple PHY processors308, other suitable network interface devices include a single PHYprocessor with multiple RF radios corresponding to respective ones ofthe communication links, in some embodiments. In some embodiments, thesingle PHY processor includes multiple baseband processors 320, while inother embodiments the single PHY processor includes a single basebandprocessor that is configured to generate multiple baseband signalscorresponding to respective communication links, and to process multiplebaseband signals received from the multiple RF radios.

In some wireless networks, one or more communication devices in thewireless network may not be capable of simultaneously transmitting andreceiving via different frequency segments, e.g., because of physicallimitations of the communication device, channel conditions, etc.Additionally or alternatively, the AP 114 may determine thatsimultaneously transmission and reception via different frequencysegments is not allowed in a WLAN, e.g., because of physical limitationsof one or more communication devices in the WLAN, channel conditions,etc.

A client station 154 informs the AP 114 whether the client station 154is capable of simultaneously transmitting and receiving via differentfrequency segments, according to an embodiment. For example, during asetup phase of an operational channel having multiple frequency links(sometimes referred to as a “multi-ink association”), the client station154 transmits to the AP 114 a frame (e.g., a management frame, a controlframe, an action frame, etc.) that includes information indicatingwhether the client station 154 is capable of simultaneously transmittingand receiving, according to an embodiment. As another example, whenjoining or seeking to join a WLAN managed by the (sometimes referred toas a “multi-ink association”), the client station 154 transmits to theAP 114 a frame (e.g., an association request frame, a reassociationrequest frame, a probe request frame, etc.) that includes informationindicating whether the client station 154 is capable of simultaneouslytransmitting and receiving, according to an embodiment.

The AP 114 informs one or more client stations 154 whether simultaneoustransmission and reception via different frequency segments is permittedin the WLAN 110, according to an embodiment. For example, during a setupphase of an operational channel having multiple frequency links(sometimes referred to as a “multi-ink association”), the AP 114transmits to one or more client stations 154 a frame (e.g., a managementframe, a control frame, an action frame, etc.) that includes informationindicating whether simultaneous transmission and reception via differentfrequency segments is permitted in the WLAN 110, according to anembodiment. As another example, when a client station 154 seeks to jointhe WLAN 110 managed by the (sometimes referred to as a “multi-inkassociation”), the AP 114 transmits to the client station 154 a frame(e.g., an association response frame, a reassociation response frame, aprobe response frame, etc.) that includes information indicating whethersimultaneous transmission and reception via different frequency segmentsis permitted in the WLAN 110, according to an embodiment. As anotherexample, the AP 114 periodically transmits a beacon frame that includesinformation indicating whether simultaneous transmission and receptionvia different frequency segments is permitted in the WLAN 110, accordingto an embodiment. As another example, when the AP 114 decides to switchfrom allowing simultaneous transmission and reception via differentfrequency segments to not permitting simultaneous transmission andreception via different frequency segments, or vice versa, the AP 114transmits a frame (e.g., a management frame, a control frame, an actionframe, etc.) that includes information indicating whether simultaneoustransmission and reception via different frequency segments is permittedin the WLAN 110, according to an embodiment.

In some embodiments, when simultaneous transmission/reception inmultiple frequency segments is not permitted (e.g., one or more of i) afirst communication device does not permit simultaneoustransmission/reception in multiple frequency segments, ii) a secondcommunication device does not permit simultaneous transmission/receptionin multiple frequency segments, iii) simultaneous transmission/receptionin multiple frequency segments is not permitted in the WLAN, etc.) andthe first communication device is transmitting unsynchronizedtransmissions in multiple frequency segments (e.g., multipletransmissions in multiple frequency segments do not begin at a sametime), the first communication device ends the unsynchronizedtransmissions in the multiple frequency segments at a same time. Whenone or more of the unsynchronized transmissions in the multiplefrequency segments prompts another communication device to transmit anacknowledgment, ending the unsynchronized transmissions at a same timehelps to avoid the one communication device transmitting in onefrequency segment at the same time that the other communication istransmitting an acknowledgment in another frequency segment, in someembodiments.

FIG. 4 is a diagram of an example of unsynchronized transmissions 400 inmultiple frequency segments corresponding to multiple communicationlinks, according to an embodiment. A first communication devicetransmits a first packet 404 in a first frequency segment correspondingto a first communication link and simultaneously transmits a secondpacket 408 in a second frequency segment corresponding to a secondcommunication link. Transmission of the first packet 404 begins prior toa beginning of transmission of the second packet 408, thus transmissionof the first packet 404 and transmission the second packet 408 begin atdifferent times.

The first communication device receives a first acknowledgment 412(e.g., an acknowledgment frame, a block acknowledgment (BA) frame, etc.,included in a packet) in the first frequency segment that is responsiveto the first packet 404. In an embodiment, a communication device thatreceives the packet 404 begins transmission of the first acknowledgment412 a defined time period after an end of reception of the packet 40. Inan embodiment, the defined time period is a short interframe space(SIFS) as defined by the IEEE 802.11 Standard. In other embodiments, thedefined time period is another suitable time duration.

Similarly, the first communication device receives a secondacknowledgment 416 (e.g., an acknowledgment frame, a BA frame, etc.,included in a packet) in the second frequency segment that is responsiveto the second packet 408. In an embodiment, a communication device thatreceives the second packet 408 begins transmission of the secondacknowledgment 416 a defined time period after an end of reception ofthe second packet 408. In an embodiment, the defined time period is SIFSas defined by the IEEE 802.11 Standard. In other embodiments, thedefined time period is another suitable time duration.

To avoid transmission of the second packet 408 occurring simultaneouslywith reception of the acknowledgment 412, the first communication deviceincludes padding information 420 in the packet 404 so that an end oftransmission of the packet 404 occurs at a same time as an end oftransmission of the packet 408. In the illustrative example of FIG. 4 ,if the padding information 420 was not included in the packet 404,reception of the acknowledgment 412 would occur earlier and overlap withtransmission of the packet 408. However, by including the paddinginformation 420 the start of reception of the acknowledgment 412 isdelayed until after an end of transmission of the second packet 408.

In some embodiments, if multiple transmissions in respective frequencysegments do not prompt acknowledgments that begin the defined timeperiod (e.g., SIFS or another suitable time duration) after an end ofthe transmission, the transmissions are permitted to end at differenttimes, and thus padding such as padding 420 is not added to a packet. Inother embodiments, even if multiple transmissions in respectivefrequency segments do not prompt acknowledgments that begin the definedtime period (e.g., SIFS or another suitable time duration) after an endof the transmission, the transmissions are required to end at a sametime.

In some embodiments, if simultaneous transmission and reception inrespective frequency segments is permitted, the transmissions arepermitted to end at different times, and thus padding such as padding420 is not added to a packet. In other embodiments, even if simultaneoustransmission and reception in respective frequency segments ispermitted, padding such as padding 420 is added to a packet so that thetransmissions end at a same time.

Although FIG. 4 illustrates an example simultaneously transmitting twopackets in two frequency segments, in other embodiments three or morepackets are simultaneously transmitted in three or more respectivefrequency segments. In some embodiments, padding is added to two or morepackets (similar to the packet 404) so that transmissions of all of thethree or packets end at a same time.

FIG. 5 is a flow diagram of an example method 500 for simultaneouslytransmitting in multiple frequency segments, according to an embodiment.In some embodiments, the multiple frequency segments correspond torespective communication links. In some embodiments, the AP 114 and/orthe client station 154 is configured to implement the method 500, andFIG. 5 is described with reference to FIG. 1 merely for explanatorypurposes. In other embodiments, the method 500 is implemented by anothersuitable communication device.

At block 504, a communication device determines (e.g., the networkinterface 122 determines, the MAC processor 126 determines, thesynchronized transmission controller 146 determines, the networkinterface 162 determines, the MAC processor 166 determines, thesynchronized transmission controller 196 determines, etc.) thatsimultaneous transmission and reception via multiple frequency segmentsis not permitted. For example, determining at block 504 thatsimultaneous transmission and reception is not permitted includes one ormore of (or none of) i) determining that the communication deviceimplementing the method 400 is not permitted to simultaneously transmitand receive in multiple frequency segments, ii) determining that anothercommunication device to which the communication device will betransmitting as part of the method 400 is not permitted tosimultaneously transmit and receive in multiple frequency segments, andiii) determining that simultaneous transmission and reception viamultiple frequency segments is not permitted in a WLAN in which thecommunication device operates, according to various embodiments.

In some embodiments, determining at block 504 that simultaneoustransmission and reception via multiple frequency segments is notpermitted includes determining that the communication device is notpermitted to simultaneously transmit and receive via multiple frequencysegments. In some embodiments, determining at block 504 thatsimultaneous transmission and reception via multiple frequency segmentsis not permitted includes receiving from another communication device apacket that includes information indicating that the other communicationdevice is not permitted to simultaneously transmit and receive viamultiple frequency segments, where the communication device will betransmitting to the other communication device as part of the method400. In some embodiments, determining at block 504 that simultaneoustransmission and reception via multiple frequency segments is notpermitted includes receiving from an AP a packet that includesinformation indicating that simultaneous transmission and reception viamultiple frequency segments is not permitted in a WLAN that is managedby the AP.

At block 508, the communication device transmits (e.g., the networkinterface 122 transmits, the PHY processor 130 transmits, the networkinterface 162 transmits, the PHY processor 170 transmits, etc.) a firstpacket in a first frequency segment beginning at a first time. At block512, the communication device transmits (e.g., the network interface 122transmits, the PHY processor 130 transmits, the network interface 162transmits, the PHY processor 170 transmits, etc.) a second packet in asecond frequency segment beginning at a second time that is differentthan the first time. Transmission of the second packet at block 512overlaps in time with transmission of the first packet at block 508.

At block 516, in response to having determined at block 504 thatsimultaneous transmission and reception via multiple frequency segmentsis not permitted, the communication device includes (e.g., the networkinterface 122 includes, the PHY processor 130 includes, the networkinterface 162 includes, the PHY processor 170 includes, etc.) in thefirst packet padding so that an end of transmission of the first packetoccurs at a same time as an end of transmission of the second packet. Insome embodiments, a MAC processor (e.g., the MAC processor 126, the MACprocessor 166, etc.) instructs a PHY processor (e.g., the PHY processor130, the PHY processor 170, etc.) to include padding in the first packetso that the end of transmission of the first packet occurs at the sametime as the end of transmission of the second packet, and the PHYprocessor (e.g., the PHY processor 130, the PHY processor 170, etc.)determines an amount of padding to include in the first packet so thatthe end of transmission of the first packet occurs at the same time asthe end of transmission of the second packet.

In some embodiments, if the communication device had determined at block504 that simultaneous transmission and reception via multiple frequencysegments is not permitted, the communication device does not include(e.g., the network interface 122 does not include, the PHY processor 130does not include, the network interface 162 does not include, the PHYprocessor 170 does not include, etc.) in the first packet padding sothat an end of transmission of the first packet occurs at a same time asan end of transmission of the second packet. In some embodiments, a MACprocessor (e.g., the MAC processor 126, the MAC processor 166, etc.)instructs a PHY processor (e.g., the PHY processor 130, the PHYprocessor 170, etc.) to not include padding in the first packet so thatthe end of transmission of the first packet occurs at the same time asthe end of transmission of the second packet, and the PHY processor(e.g., the PHY processor 130, the PHY processor 170, etc.). In someembodiments, padding is nonetheless added for other purposes other thanfor ensuring that the end of transmission of the first packet occurs atthe same time as the end of transmission of the second packet, such asto ensure that the modulated information ends on an OFDM symbolboundary, to add a packet extension to allow a receiver device more timeto generate a response to the packet, etc.

In some embodiments, a communication device in a WLAN simultaneously andsynchronously transmits in multiple frequency segments, e.g., themultiple transmissions in multiple frequency segments begin at a sametime. In some embodiments, a communication device in a WLAN isconfigured to both: i) simultaneously transmit in multiple frequencysegments, where the multiple transmissions in multiple frequencysegments are required to begin at a same time, and ii) simultaneouslyand synchronously transmits in multiple frequency segments, e.g., themultiple transmissions in multiple frequency segments are required tobegin at a same time. For example, in some embodiments, at some timesand/or in some situations, simultaneously transmissions in multiplefrequency segments are required to begin at a same time, whereas atother times and/or in other situations, simultaneously transmissions inmultiple frequency segments are permitted to begin at different times.As an example, whether simultaneous transmissions in multiple frequencysegments are required to begin at a same time depends on a distance, infrequency, between the multiple frequency segments, according to someembodiments. For instance, in an illustrative embodiment, when a firstfrequency segment is in the 2.4 GHz band and a second frequency segmentis in the 6 GHz band, simultaneous transmissions in multiple frequencysegments are permitted to begin different times. On the other hand, asanother example, when a first frequency segment is in the 5 GHz band anda second frequency segment is in the 6 GHz band, or if the first andsecond frequency segments are in the same RF band, simultaneoustransmissions in multiple frequency segments are required to begin at asame time, according to another illustrative embodiment.

In some embodiments involving simultaneous and synchronous transmissionsin multiple frequency segments, the communication device performsrespective backoff operations (using multiple backoff counters) inmultiple frequency segments (e.g., a respective backoff operation ineach of the multiple frequency segments) and begins the simultaneous andsynchronous transmissions in multiple frequency segments in response toall of the backoff counters expiring (e.g., all of the backoff countersreaching zero).

FIG. 6 is a flow diagram of an example method 600 for simultaneouslytransmitting in multiple frequency segments beginning at a same time,according to another embodiment. In some embodiments, the multiplefrequency segments correspond to respective communication links. In someembodiments, the AP 114 and/or the client station 154 are configured toimplement the method 600, and FIG. 6 is described with reference to FIG.1 merely for explanatory purposes. In other embodiments, the method 500is implemented by another suitable communication device.

At block 604, a communication device determines (e.g., the networkinterface 122 determines, the MAC processor 126 determines, the backoffcontroller 140 determines, the network interface 162 determines, the MACprocessor 166 determines, the backoff controller 190 determines, etc.)whether multiple backoff counters (e.g., backoff counters 142, backoffcounters 192, etc.) corresponding to multiple frequency segments of anoperating channel are expired (e.g., have reached zero). For example, inan embodiment, the communication device maintains (e.g., the networkinterface 122 maintains, the MAC processor 126 maintains, the backoffcontroller 140 maintains, the network interface 162 maintains, the MACprocessor 166 maintains, the backoff controller 190 maintains, etc.)respective backoff counters 142/192 for respective frequency segment. Inan embodiment, each backoff counter 142/192 corresponds to a respectivesubchannel in the respective frequency segment, and the backoff counter142/192 is decremented when the respective subchannel is determined tobe idle and is suspended when the respective subchannel is determined tobe busy. In an embodiment, each backoff counter 142/192 corresponds to arespective primary subchannel in the respective frequency segment, andthe backoff counter 142/192 is decremented when the respective primarysubchannel is determined to be idle and is suspended when the respectiveprimary subchannel is determined to be busy.

In response to determining, at block 604, that not all of the multiplebackoff counters are expired (e.g., that one or more of the backoffcounters are not expired), the communication device waits (e.g., thenetwork interface 122 waits, the MAC processor 126 waits, the backoffcontroller 140 waits, the network interface 162 waits, the MAC processor166 waits, the backoff controller 190 waits, etc.) until all of themultiple backoff counters are expired.

In some embodiments, when one backoff counter is expired but one or moreother backoff counters are not expired, the method 600 includes waitinguntil all of the backoff counters are expired.

In response to determining, at block 604, that all of the multiplebackoff counters are expired, the flow proceeds to block 608. At block608, the communication device determines whether all of any secondarysubchannels in the operating channel are idle for a determined timeperiod prior to a beginning of transmission in the operating channel. Inan embodiment, the defined time period is a suitable time duration suchas a point coordination function (PCF) interframe space (PIFS) asdefined by the IEEE 802.11 Standard. In other embodiments, the definedtime period is another suitable time duration such as a distributedcoordination function (DCF) interframe space (DIFS) as defined by theIEEE 802.11 Standard, SIFS as defined by the IEEE 802.11 Standard, oranother suitable time duration.

In response to determining, at block 608, that not all of the secondarysubchannels in the operating channel are idle for the determined timeperiod prior to the beginning of transmission in the operating channel(e.g., that one or more of the secondary subchannels are busy), the flowproceeds to block 612. At block 612, a transmission in the operatingchannel is not performed. In some embodiments, in connection with block612, the multiple backoff counters are reset and the flow 600 isrepeated. In another embodiment, a transmission in i) multiple primarysubchannels corresponding to the multiple backoff counters and ii) oneor more secondary subchannels that are idle (if any) is performed.

On the other hand, in response to determining, at block 608, that all ofthe secondary subchannels in the operating channel are idle for thedetermined time period prior to the beginning of transmission in theoperating channel (e.g., that one or more of the secondary subchannelsare busy), the flow proceeds to block 616. At block 616, a transmissionin the operating channel is performed, including simultaneouslytransmitting in multiple frequency segments beginning at a same time.

FIG. 7 is a diagram of an illustrative example of a simultaneoustransmission in multiple frequency segments beginning at a same time,according to an embodiment. The transmission 700 is performed inaccordance with the method 600 of FIG. 6 , in some embodiments. In otherembodiments, the transmission 700 is performed in accordance withanother suitable method for simultaneously transmitting in multiplefrequency segments beginning at a same time.

The transmission 700 is within an operating channel that includes afirst frequency segment and a second frequency segment. In someembodiments, the first frequency segment corresponds to a firstcommunication link and the second frequency segment corresponds to asecond communication link.

A communication device performs (e.g., the network interface 122performs, the MAC processor 126 performs, the backoff controller 140performs, the network interface 162 performs, the MAC processor 166performs, the backoff controller 190 performs, etc.) a first backoffprocedure 704 in connection with a first frequency segment, and performs(e.g., the network interface 122 performs, the MAC processor 126performs, the backoff controller 140 performs, the network interface 162performs, the MAC processor 166 performs, the backoff controller 190performs, etc.) a second backoff procedure 708 in connection with asecond frequency segment.

In some embodiments, performing the backoff procedure 704 includesdecrementing a first backoff counter when a subchannel within the firstfrequency segment is determined to be idle, and pausing decrementing ofthe first backoff counter when the subchannel within the first frequencysegment is determined to be not idle (e.g., busy). In some embodiments,performing the backoff procedure 704 includes decrementing a firstbackoff counter when a primary subchannel within the first frequencysegment is determined to be idle, and pausing decrementing of the firstbackoff counter when the primary subchannel within the first frequencysegment is determined to be not idle (e.g., busy).

In some embodiments, performing the backoff procedure 708 includesdecrementing a second backoff counter when a subchannel within thesecond frequency segment is determined to be idle, and pausingdecrementing of the second backoff counter when the subchannel withinthe second frequency segment is determined to be not idle (e.g., busy).In some embodiments, performing the backoff procedure 708 includesdecrementing a second backoff counter when a primary subchannel withinthe second frequency segment is determined to be idle, and pausingdecrementing of the second backoff counter when the primary subchannelwithin the second frequency segment is determined to be not idle (e.g.,busy).

In the example transmission 700 of FIG. 7 , the first backoff counterexpires prior to the second backoff counter expiring. In response to thefirst backoff counter expiring prior to the second backoff counterexpiring, the communication device defers transmitting (e.g., waits totransmit) in the first frequency segment until the second backoffcounter expires. In response to the second backoff counter expiring, thecommunication transmits (e.g., the network interface 122 transmits, thePHY processor 130 transmits, the network interface 162 transmits, thePHY processor 170 transmits, etc.) a transmission 720 that includes afirst transmission 724 in the first frequency segment and a secondtransmission 728 in the second frequency segment. The first transmission724 and the second transmission 728 begin at a same time.

In an embodiment, the first transmission 724 comprises a first PHY dataunit and the second transmission 728 comprises a PHY data unit packet.In another embodiment, the first transmission 724 and the secondtransmission 728 correspond to a single PHY data unit that spans theoperating channel.

FIG. 8 is a diagram of another illustrative example of a simultaneoustransmission in multiple frequency segments beginning at a same time,according to another embodiment. The transmission 800 is performed inaccordance with the method 600 of FIG. 6 , in some embodiments. In otherembodiments, the transmission 800 is performed in accordance withanother suitable method for simultaneously transmitting in multiplefrequency segments beginning at a same time.

The transmission 800 is within an operating channel that includes afirst frequency segment and a second frequency segment. In someembodiments, the first frequency segment corresponds to a firstcommunication link and the second frequency segment corresponds to asecond communication link.

The transmission 800 is similar to the transmission 700 of FIG. 7 , andlike-numbered elements are not described in detail for purposes ofbrevity.

In response to the first backoff counter expiring prior to the secondbackoff counter expiring, the communication device defers transmitting(e.g., waits to transmit) the transmission 724 and transmits a paddingsignal 804 until the second backoff counter expires. In response to thesecond backoff counter expiring, the communication stops transmittingthe padding signal 804 and begins transmitting (e.g., the networkinterface 122 transmits, the PHY processor 130 transmits, the networkinterface 162 transmits, the PHY processor 170 transmits, etc.) thetransmission 720 that includes the first transmission 724 in the firstfrequency segment and the second transmission 728 in the secondfrequency segment. In an embodiment, the transmission 724 includes a PHYpreamble with a training field (e.g., a legacy short training field(L-STF) or another suitable training field) that is used by receiversfor packet detection, among other things. In some embodiments, thepadding signal 804 has a low cross-correlation with the training fieldin the PHY preamble used by receivers for packet detection so that aprobability of receivers mistaking the padding signal 804 for abeginning of a packet is low. Additionally or alternatively, the paddingsignal 804 is configured to prompt receiver devices to determine thatthat the subchannel(s) in which the padding signal 804 is transmittedis/are busy, which increases the probability that other communicationdevices will not attempt to transmit in the subchannel(s) correspondingto the first transmission 724 between when the first backoff counterexpires and when the second backoff counter expires, according to someembodiments.

Although FIGS. 7 and 8 illustrate example simultaneous transmissions intwo frequency segments, in other embodiments three or more transmissionsare simultaneously transmitted in three or more respective frequencysegments. With respect to FIG. 8 , in some embodiments, padding istransmitted in two or more frequency segments.

Referring now to FIGS. 6-8 , when a frame transmission fails inconnection with a simultaneous transmission in multiple frequencysegments (e.g., failure to receive an acknowledgment of the frame), thevalue of CW is adjusted (e.g., is approximately doubled with an upperbound of CWmax) for only one of the backoff counters (e.g., the value ofCW for one or more other backoff counters is kept the same), accordingto an embodiment. When a frame transmission in one frequency segmentfails in connection with a simultaneous transmission in multiplefrequency segments (e.g., failure to receive an acknowledgment of theframe), the value of CW is adjusted (e.g., is approximately doubled withan upper bound of CWmax) for only the backoff counter that correspondsto the one frequency segment (e.g., the value of CW for one or moreother backoff counters is kept the same), according to an embodiment. Inother embodiments, when a frame transmission in one frequency segmentfails in connection with a simultaneous transmission in multiplefrequency segments (e.g., failure to receive an acknowledgment of theframe), the value of CW is adjusted (e.g., is approximately doubled withan upper bound of CWmax) for all of the backoff counters.

FIG. 9 is a flow diagram of another example method 900 forsimultaneously transmitting in multiple frequency segments beginning ata same time, according to another embodiment. In some embodiments, themultiple frequency segments correspond to respective communicationlinks. In some embodiments, the AP 114 and/or the client station 154 areconfigured to implement the method 900, and FIG. 9 is described withreference to FIG. 1 merely for explanatory purposes. In otherembodiments, the method 500 is implemented by another suitablecommunication device.

At block 904, a communication device determines (e.g., the networkinterface 122 determines, the MAC processor 126 determines, the backoffcontroller 140 determines, the network interface 162 determines, the MACprocessor 166 determines, the backoff controller 190 determines, etc.)whether a single backoff counter (e.g., backoff counter 142, backoffcounter 192, etc.) corresponding to a single frequency segment of anoperating channel is expired (e.g., has reached zero). In an embodiment,the backoff counter 142/192 corresponds to a subchannel within thesingle frequency segment, and the backoff counter 142/192 is decrementedwhen the subchannel is determined to be idle and decrementing issuspended when the subchannel is determined to be busy. In anembodiment, the backoff counter 142/192 corresponds to a primarysubchannel within the single frequency segment, and the backoff counter142/192 is decremented when the primary subchannel is determined to beidle and decrementing is suspended when the primary subchannel isdetermined to be busy.

In response to determining, at block 904, that the single backoffcounter has not expired, the communication device waits (e.g., thenetwork interface 122 waits, the MAC processor 126 waits, the backoffcontroller 140 waits, the network interface 162 waits, the MAC processor166 waits, the backoff controller 190 waits, etc.) until the singlebackoff counter expires.

In response to determining, at block 904, that the single backoffcounter has expired, the flow proceeds to block 908. At block 908, thecommunication device determines whether all of the other subchannels(e.g., subchannels other than the primary subchannel corresponding tothe backoff counter) in the operating channel are idle for a determinedtime period prior to a beginning of transmission in the operatingchannel. In an embodiment, the defined time period is a suitable timeduration such as PIFS as defined by the IEEE 802.11 Standard. In otherembodiments, the defined time period is another suitable time durationsuch as a DIFS as defined by the IEEE 802.11 Standard, SIFS as definedby the IEEE 802.11 Standard, or another suitable time duration.

In response to determining, at block 908, that not all of the othersubchannels in the operating channel are idle for the determined timeperiod prior to the beginning of transmission in the operating channel(e.g., that one or more of the other subchannels are busy), the flowproceeds to block 912. At block 912, a transmission in the operatingchannel is not performed. In some embodiments, in connection with block912, the single backoff counter is reset and the flow 900 is repeated.In another embodiment, a transmission in i) the primary subchannelcorresponding to the backoff counters and ii) one or more othersubchannels that are idle (if any) is performed.

On the other hand, in response to determining, at block 908, that all ofthe other subchannels in the operating channel are idle for thedetermined time period prior to the beginning of transmission in theoperating channel (e.g., that one or more of the secondary subchannelsare busy), the flow proceeds to block 916. At block 916, a transmissionin the operating channel is performed, including simultaneouslytransmitting in multiple frequency segments beginning at a same time.

FIG. 10 is a diagram of an illustrative example of a simultaneoustransmission in multiple frequency segments beginning at a same time,according to an embodiment. The transmission 1000 is performed inaccordance with the method 900 of FIG. 9 , in some embodiments. In otherembodiments, the transmission 1000 is performed in accordance withanother suitable method for simultaneously transmitting in multiplefrequency segments beginning at a same time.

The transmission 1000 is within an operating channel that includes afirst frequency segment and a second frequency segment. In someembodiments, the first frequency segment corresponds to a firstcommunication link and the second frequency segment corresponds to asecond communication link.

A communication device performs (e.g., the network interface 122performs, the MAC processor 126 performs, the backoff controller 140performs, the network interface 162 performs, the MAC processor 166performs, the backoff controller 190 performs, etc.) a backoff procedure1004 in connection with a first frequency segment. In some embodiments,performing the backoff procedure 1004 includes decrementing a backoffcounter when a subchannel within the first frequency segment isdetermined to be idle, and pausing decrementing of the backoff counterwhen the subchannel within the first frequency segment is determined tobe not idle (e.g., busy). In some embodiments, performing the backoffprocedure 1004 includes decrementing the backoff counter when a primarysubchannel within the first frequency segment is determined to be idle,and pausing decrementing of the backoff counter when the primarysubchannel within the first frequency segment is determined to be notidle (e.g., busy).

In response to the backoff counter expiring, the communication transmits(e.g., the network interface 122 transmits, the PHY processor 130transmits, the network interface 162 transmits, the PHY processor 170transmits, etc.) a transmission 1020 that includes a first transmission1024 in the first frequency segment and a second transmission 1028 inthe second frequency segment. The first transmission 1024 and the secondtransmission 1028 begin at a same time.

In an embodiment, the first transmission 1024 comprises a first PHY dataunit and the second transmission 1028 comprises a PHY data unit packet.In another embodiment, the first transmission 1024 and the secondtransmission 1028 correspond to a single PHY data unit that spans theoperating channel.

In some embodiments, the frequency segment in which a backoff procedureis performed for transmissions over multiple frequency segments andbeginning at a same time is changed over time. For example, in someembodiments, in connection with a first transmission in multiplefrequency segments, a communication device chooses a frequency segment,from among the multiple frequency segments, for performing a backoffprocedure that is different than another frequency segment in which abackoff procedure was used for a previous second transmission via themultiple frequency segments.

FIG. 11 is a diagram of an illustrative example of a plurality of setsof simultaneous transmissions 1100, according to an embodiment. Each ofthe sets of transmissions in the plurality of sets of transmissions 1100is performed in accordance with the method 900 of FIG. 9 , in someembodiments. In other embodiments, each of the sets of transmissions inthe plurality of sets of transmissions 1100 is performed in accordancewith another suitable method for simultaneously transmitting in multiplefrequency segments beginning at a same time.

The sets of transmissions 1100 are within an operating channel thatincludes a first frequency segment and a second frequency segment. Insome embodiments, the first frequency segment corresponds to a firstcommunication link and the second frequency segment corresponds to asecond communication link.

In connection with a first set of transmissions 1104, a communicationdevice performs (e.g., the network interface 122 performs, the MACprocessor 126 performs, the backoff controller 140 performs, the networkinterface 162 performs, the MAC processor 166 performs, the backoffcontroller 190 performs, etc.) a backoff procedure 1108 in connectionwith a first frequency segment. In some embodiments, performing thebackoff procedure 1108 includes decrementing a backoff counter when asubchannel within the first frequency segment is determined to be idle,and pausing decrementing of the backoff counter when the subchannelwithin the first frequency segment is determined to be not idle (e.g.,busy). In some embodiments, performing the backoff procedure 1108includes decrementing the backoff counter when a primary subchannelwithin the first frequency segment is determined to be idle, and pausingdecrementing of the backoff counter when the primary subchannel withinthe first frequency segment is determined to be not idle (e.g., busy).

In response to the backoff counter expiring, the communication transmits(e.g., the network interface 122 transmits, the PHY processor 130transmits, the network interface 162 transmits, the PHY processor 170transmits, etc.) the set of transmissions 1104, which includes a firsttransmission 1124 in the first frequency segment and a secondtransmission 1128 in the second frequency segment. The firsttransmission 1124 and the second transmission 1128 begin at a same time.

In an embodiment, the first transmission 1124 comprises a first PHY dataunit and the second transmission 1128 comprises a PHY data unit packet.In another embodiment, the first transmission 1124 and the secondtransmission 1128 correspond to a single PHY data unit that spans theoperating channel.

In connection with a second set of transmissions 1134, the communicationdevice performs (e.g., the network interface 122 performs, the MACprocessor 126 performs, the backoff controller 140 performs, the networkinterface 162 performs, the MAC processor 166 performs, the backoffcontroller 190 performs, etc.) a backoff procedure 1138 in connectionwith the second frequency segment. In some embodiments, performing thebackoff procedure 1138 includes decrementing a backoff counter when asubchannel within the second frequency segment is determined to be idle,and pausing decrementing of the backoff counter when the subchannelwithin the second frequency segment is determined to be not idle (e.g.,busy). In some embodiments, performing the backoff procedure 1138includes decrementing the backoff counter when a primary subchannelwithin the second frequency segment is determined to be idle, andpausing decrementing of the backoff counter when the primary subchannelwithin the second frequency segment is determined to be not idle (e.g.,busy).

In response to the backoff counter expiring, the communication transmits(e.g., the network interface 122 transmits, the PHY processor 130transmits, the network interface 162 transmits, the PHY processor 170transmits, etc.) the set of transmissions 1134, which includes a firsttransmission 1144 in the first frequency segment and a secondtransmission 1148 in the second frequency segment. The firsttransmission 1144 and the second transmission 1148 begin at a same time.

In an embodiment, the first transmission 1144 comprises a first PHY dataunit and the second transmission 1148 comprises a PHY data unit packet.In another embodiment, the first transmission 1144 and the secondtransmission 1148 correspond to a single PHY data unit that spans theoperating channel.

In connection with a third set of transmissions 1154, the communicationdevice performs (e.g., the network interface 122 performs, the MACprocessor 126 performs, the backoff controller 140 performs, the networkinterface 162 performs, the MAC processor 166 performs, the backoffcontroller 190 performs, etc.) a backoff procedure 1158 in connectionwith the first frequency segment. In some embodiments, performing thebackoff procedure 1158 includes decrementing a backoff counter when asubchannel within the first frequency segment is determined to be idle,and pausing decrementing of the backoff counter when the subchannelwithin the first frequency segment is determined to be not idle (e.g.,busy). In some embodiments, performing the backoff procedure 1158includes decrementing the backoff counter when a primary subchannelwithin the first frequency segment is determined to be idle, and pausingdecrementing of the backoff counter when the primary subchannel withinthe first frequency segment is determined to be not idle (e.g., busy).

In response to the backoff counter expiring, the communication transmits(e.g., the network interface 122 transmits, the PHY processor 130transmits, the network interface 162 transmits, the PHY processor 170transmits, etc.) the set of transmissions 1154, which includes a firsttransmission 1164 in the first frequency segment and a secondtransmission 1168 in the second frequency segment. The firsttransmission 1164 and the second transmission 1168 begin at a same time.

In an embodiment, the first transmission 1164 comprises a first PHY dataunit and the second transmission 1168 comprises a PHY data unit packet.In another embodiment, the first transmission 1164 and the secondtransmission 1168 correspond to a single PHY data unit that spans theoperating channel.

Although FIGS. 10 and 11 illustrate example simultaneous transmissionsin two frequency segments, in other embodiments three or moretransmissions are simultaneously transmitted in three or more respectivefrequency segments. With respect to FIG. 11 , in some embodiments,backoff operations are performed in three or more frequency segments.

FIGS. 9-11 describe performing a backoff operation in only frequencysegment using only one backoff counter. In some embodiments, thecommunication device maintains (e.g., the network interface 122maintains, the MAC processor 126 maintains, the backoff controller 140maintains, the network interface 162 maintains, the MAC processor 166maintains, the backoff controller 190 maintains, etc.) multiple backoffcounters for multiple frequency segments, and backoff counterscorresponding to other frequency segments are ignored at least when theone backoff counter corresponding to the one frequency segment expires.In an embodiment, when another backoff counter corresponding to anotherfrequency segment expires, the other backoff counter is reset asdiscussed above. In an embodiment, when another backoff countercorresponding to another frequency segment expires, the value of CW isincreased and the other backoff counter is reset as discussed above. Inan embodiment, the value of CW is increased by adding a value randomlyor pseudorandomly selected from the range [0, 1]. In another embodiment,when another backoff counter corresponding to another frequency segmentexpires, the value of CW kept the same and the other backoff counter isreset as discussed above.

Referring to FIGS. 9-11 , when a frame transmission fails in connectionwith a simultaneous transmission in multiple frequency segments (e.g.,failure to receive an acknowledgment of the frame), the value of CW isadjusted (e.g., is approximately doubled with an upper bound of CWmax)for only one of the backoff counters (e.g., the value of CW for one ormore other backoff counters is kept the same), according to anembodiment. When a frame transmission in one frequency segment fails inconnection with a simultaneous transmission in multiple frequencysegments (e.g., failure to receive an acknowledgment of the frame), thevalue of CW is adjusted (e.g., is approximately doubled with an upperbound of CWmax) for only the backoff counter that corresponds to the onefrequency segment (e.g., the value of CW for one or more other backoffcounters is kept the same), according to an embodiment. In otherembodiments, when a frame transmission in one frequency segment fails inconnection with a simultaneous transmission in multiple frequencysegments (e.g., failure to receive an acknowledgment of the frame), thevalue of CW is adjusted (e.g., is approximately doubled with an upperbound of CWmax) for all of the backoff counters.

In various embodiments discussed above, the communication devicedetermines whether a subchannel is idle by comparing an energy levelmeasured in the subchannel to a threshold. In some embodiments, thecommunication device additionally or alternatively determines (e.g., thenetwork interface 122 determines, the MAC processor 126 determines, thebackoff controller 140 determines, the network interface 162 determines,the MAC processor 166 determines, the backoff controller 190 determines,etc.) whether a subchannel is idle by determining whether a networkallocation vector (NAV) counter corresponding to the subchannel isexpired. In some embodiments, the NAV counter indicates whether anothercommunication device has seized a communication medium. For example, theNAV counter is set using duration information in a received frame, andthe NAV counter is decremented at a predetermined rate. When the NAVcounter expires (e.g., reaches zero), this indicates that no othercommunication device is currently in control of the communicationmedium.

Embodiment 1: A method for simultaneously transmitting in multiplefrequency segments, comprising: determining, at a communication device,that simultaneous transmission and reception via multiple frequencysegments is not permitted; transmitting, by the communication device, afirst packet in a first frequency segment beginning at a first time;transmitting, by the communication device, a second packet in a secondfrequency segment beginning at a second time that is different than thefirst time, wherein transmission of the second packet overlaps in timewith transmission of the first packet; and in response to havingdetermined that simultaneous transmission and reception via multiplefrequency segments is not permitted, including in the first packetpadding so that an end of transmission of the first packet occurs at asame time as an end of transmission of the second packet.

Embodiment 2: The method of embodiment 1, wherein determining thatsimultaneous transmission and reception via multiple frequency segmentsis not permitted comprises: determining that the communication device isnot permitted to simultaneously transmit and receive via multiplefrequency segments.

Embodiment 3: The method of embodiment 1, wherein the communicationdevice is a first communication device, and wherein: transmitting thesecond packet in the second frequency segment comprises transmitting thesecond packet to a second communication device in the second frequencysegment; and determining that simultaneous transmission and receptionvia multiple frequency segments is not permitted comprises: determiningthat the second communication device is not permitted to simultaneouslytransmit and receive via multiple frequency segments.

Embodiment 4: The method of embodiment 3, wherein that the secondcommunication device is not permitted to simultaneously transmit andreceive via multiple frequency segments comprises: receiving, at thefirst communication device, a third packet from the second communicationdevice, the third packet including information indicating that thesecond communication device is not permitted to simultaneously transmitand receive via multiple frequency segments.

Embodiment 5: The method of embodiment 1, wherein determining thatsimultaneous transmission and reception via multiple frequency segmentsis not permitted comprises: determining that simultaneous transmissionand reception via multiple frequency segments is not permitted in awireless local area network (WLAN) to which the communication devicebelongs.

Embodiment 6: The method of embodiment 5, wherein determining thatsimultaneous transmission and reception via multiple frequency segmentsis not permitted in the WLAN comprises: receiving, at the communicationdevice, a third packet from an access point that manages the WLAN, thethird packet including information indicating that simultaneoustransmission and reception via multiple frequency segments is notpermitted in the WLAN.

Embodiment 7: The method of any of embodiments 1-6, further comprising:in response to determining that simultaneous transmission and receptionvia multiple frequency segments is not permitted, prompting a physicallayer (PHY) processor of the communication device to include in thefirst packet the padding so that the end of transmission of the firstpacket occurs at the same time as the end of transmission of the secondpacket.

Embodiment 8: A first communication device, comprising a wirelessnetwork interface device that is configured to communicate via multiplefrequency segments. The wireless network interface device includes oneor more integrated circuit (IC) devices configured to: determine thatsimultaneous transmission and reception via multiple frequency segmentsis not permitted; control the wireless network interface device totransmit a first packet in a first frequency segment beginning at afirst time; control the wireless network interface device to transmit asecond packet in a second frequency segment beginning at a second timethat is different than the first time, wherein transmission of thesecond packet overlaps in time with transmission of the first packet;and in response to having determined that simultaneous transmission andreception via multiple frequency segments is not permitted, include inthe first packet padding so that an end of transmission of the firstpacket occurs at a same time as an end of transmission of the secondpacket.

Embodiment 9: The first communication device of embodiment 8, whereinthe one or more IC devices are configured to: determine that the firstcommunication device is not permitted to simultaneously transmit andreceive via multiple frequency segments.

Embodiment 10: The first communication device of embodiment 8, whereinthe one or more IC devices are configured to: control the wirelessnetwork interface device to transmit the second packet to a secondcommunication device in the second frequency segment; and determine thatsimultaneous transmission and reception via multiple frequency segmentsis not permitted at least by determining that the second communicationdevice is not permitted to simultaneously transmit and receive viamultiple frequency segments.

Embodiment 11: The first communication device of embodiment 10, whereinthe one or more IC devices are configured to: determine that the secondcommunication device is not permitted to simultaneously transmit andreceive via multiple frequency segments using information in a thirdpacket, received from the second communication device, the informationin the third packet indicating that the second communication device isnot permitted to simultaneously transmit and receive via multiplefrequency segments.

Embodiment 12: The first communication device of embodiment 8, whereinthe one or more IC devices are configured to: determine thatsimultaneous transmission and reception via multiple frequency segmentsis not permitted at least by determining that simultaneous transmissionand reception via multiple frequency segments is not permitted in a WLANto which the communication device belongs.

Embodiment 13: The first communication device of embodiment 12, whereinthe one or more IC devices are configured to: determine thatsimultaneous transmission and reception via multiple frequency segmentsis not permitted in the WLAN using information in a third packet,received from an access point that manages the WLAN, the information inthe third packet indicating that simultaneous transmission and receptionvia multiple frequency segments is not permitted in the WLAN.

Embodiment 14: The first communication device of any of embodiments8-13, wherein: the wireless network interface comprises a physical layer(PHY) processor implemented on the one or more IC devices; and the oneor more IC devices are configured to, in response to determining thatsimultaneous transmission and reception via multiple frequency segmentsis not permitted, prompt the PHY processor to include in the firstpacket the padding so that the end of transmission of the first packetoccurs at the same time as the end of transmission of the second packet.

Embodiment 15: A method for simultaneously transmitting in multiplefrequency segments, comprising: performing, at a communication device, abackoff operation corresponding to one frequency segment among themultiple frequency segments, the backoff operation involvingdecrementing a backoff counter in connection with the one frequencysegment; determining, at a communication device, whether the backoffcounter of the communication device is expired; and in response todetermining that the backoff counter has expired, simultaneouslytransmitting, by the communication device, respective transmissions inrespective frequency segments beginning at a same time.

Embodiment 16: The method of embodiment 15, further comprising:decrementing, by the communication device, the backoff counter when asubchannel in the one frequency segment is determined to be idle; andsuspending, by the communication device, the decrementing of the backoffcounter when the subchannel in the one frequency segment is determinedto be busy.

Embodiment 17: The method of embodiment 16, further comprising: inconnection with determining that the backoff counter has expired,determining, at the communication device, whether one or more othersubchannels in the multiple frequency segments are idle for apredetermined time period prior to a beginning of the respectivetransmissions in respective frequency segments; wherein simultaneouslytransmitting the respective transmissions in the respective frequencysegments beginning at the same time is further in response todetermining that the one or more other subchannels in the multiplefrequency segments are idle for the predetermined time period.

Embodiment 18: The method of embodiment 17, further comprising: inresponse to determining that one or more other subchannels in themultiple frequency segments are busy during the predetermined timeperiod, determining to postpone the simultaneous transmission of therespective transmissions in the respective frequency segments.

Embodiment 19: The method of any of embodiments 15-18, wherein, inconnection with a subsequent simultaneous transmission in multiplefrequency segments: selecting, at the communication device, anotherfrequency segment different than the one frequency segment; performing,at the communication device, another backoff operation corresponding tothe other frequency segment different than the one frequency segment,the other backoff operation including decrementing the backoff counteror another backoff counter in connection with the other frequencysegment; determining, at a communication device, whether the backoffcounter or the other backoff counter is expired; and in response todetermining that the backoff counter or the other backoff counter hasexpired, performing, by the communication device, the subsequentsimultaneous transmission in the multiple frequency segments.

Embodiment 20: The method of any of embodiments 15-18 combined with themethod of any of embodiments 1-7.

Embodiment 21: A communication device, comprising: a wireless networkinterface device that is configured to communicate via multiplefrequency segments, the wireless network interface device including oneor more IC devices and a backoff counter implemented on the one or moreIC devices. The one or more IC devices are configured to: perform abackoff operation corresponding to one frequency segment among themultiple frequency segments, the backoff operation involvingdecrementing the backoff counter in connection with the one frequencysegment; determine whether the backoff counter is expired; and inresponse to determining that the backoff counter has expired, controlthe wireless network interface device to simultaneously transmitrespective transmissions in respective frequency segments beginning at asame time.

Embodiment 22: The communication device of embodiment 21, wherein theone or more IC devices are further configured to: decrement the backoffcounter when a subchannel in the one frequency segment is determined tobe idle; and suspend the decrementing of the backoff counter when thesubchannel in the one frequency segment is determined to be busy.

Embodiment 23: The communication device of embodiment 22, wherein theone or more IC devices are further configured to: in connection withdetermining that the backoff counter has expired, determine whether oneor more other subchannels in the multiple frequency segments are idlefor a predetermined time period prior to a beginning of the respectivetransmissions in respective frequency segments; and control the wirelessnetwork interface device to simultaneously transmit the respectivetransmissions in the respective frequency segments further in responseto determining that the one or more other subchannels in the multiplefrequency segments are idle for the predetermined time period.

Embodiment 24: The communication device of embodiment 23, wherein theone or more IC devices are further configured to: in response todetermining that one or more other subchannels in the multiple frequencysegments are busy during the predetermined time period, determine topostpone the simultaneous transmission of the respective transmissionsin the respective frequency segments.

Embodiment 25: The communication device of any of embodiments 21-24,wherein the one or more IC devices are further configured to, inconnection with a subsequent simultaneous transmission in multiplefrequency segments: select another frequency segment different than theone frequency segment; perform another backoff operation correspondingto the other frequency segment different than the one frequency segment,the other backoff operation including decrementing the backoff counteror another backoff counter in connection with the other frequencysegment; determine whether the backoff counter or the other backoffcounter is expired; and in response to determining that the backoffcounter or the other backoff counter has expired, control the wirelessnetwork interface device to perform the subsequent simultaneoustransmission in the multiple frequency segments.

Embodiment 26: The communication device of any of embodiments 21-25wherein the one or more IC devices are further configured to perform theacts recited in any of embodiments 8-14.

At least some of the various blocks, operations, and techniquesdescribed above may be implemented utilizing hardware, a processorexecuting firmware instructions, a processor executing softwareinstructions, or any combination thereof. When implemented utilizing aprocessor executing software or firmware instructions, the software orfirmware instructions may be stored in any suitable computer readablememory such as a random access memory (RAM), a read only memory (ROM), aflash memory, etc. The software or firmware instructions may includemachine readable instructions that, when executed by one or moreprocessors, cause the one or more processors to perform various acts.

When implemented in hardware, the hardware may comprise one or more ofdiscrete components, an integrated circuit, an application-specificintegrated circuit (ASIC), a programmable logic device (PLD), etc.

While the present invention has been described with reference tospecific examples, which are intended to be illustrative only and not tobe limiting of the invention, changes, additions and/or deletions may bemade to the disclosed embodiments without departing from the scope ofthe invention.

What is claimed is:
 1. A method for simultaneously transmitting inmultiple frequency segments, comprising: determining, at a communicationdevice, that simultaneous transmission and reception via multiplefrequency segments is not permitted; transmitting, by the communicationdevice, a first packet in a first frequency segment beginning at a firsttime; transmitting, by the communication device, a second packet in asecond frequency segment beginning at a second time that is differentthan the first time, wherein transmission of the second packet overlapsin time with transmission of the first packet; and in response to havingdetermined that simultaneous transmission and reception via multiplefrequency segments is not permitted, including in the first packetpadding so that an end of transmission of the first packet occurs at asame time as an end of transmission of the second packet.
 2. The methodof claim 1, wherein determining that simultaneous transmission andreception via multiple frequency segments is not permitted comprises:determining that the communication device is not permitted tosimultaneously transmit and receive via multiple frequency segments. 3.The method of claim 1, wherein the communication device is a firstcommunication device, and wherein: transmitting the second packet in thesecond frequency segment comprises transmitting the second packet to asecond communication device in the second frequency segment; anddetermining that simultaneous transmission and reception via multiplefrequency segments is not permitted comprises: determining that thesecond communication device is not permitted to simultaneously transmitand receive via multiple frequency segments.
 4. The method of claim 3,wherein determining that the second communication device is notpermitted to simultaneously transmit and receive via multiple frequencysegments comprises: receiving, at the first communication device, athird packet from the second communication device, the third packetincluding information indicating that the second communication device isnot permitted to simultaneously transmit and receive via multiplefrequency segments.
 5. The method of claim 1, wherein determining thatsimultaneous transmission and reception via multiple frequency segmentsis not permitted comprises: determining that simultaneous transmissionand reception via multiple frequency segments is not permitted in awireless local area network (WLAN) to which the communication devicebelongs.
 6. The method of claim 5, wherein determining that simultaneoustransmission and reception via multiple frequency segments is notpermitted in the WLAN comprises: receiving, at the communication device,a third packet from an access point that manages the WLAN, the thirdpacket including information indicating that simultaneous transmissionand reception via multiple frequency segments is not permitted in theWLAN.
 7. The method of claim 1, further comprising: in response todetermining that simultaneous transmission and reception via multiplefrequency segments is not permitted, prompting a physical layer (PHY)processor of the communication device to include in the first packet thepadding so that the end of transmission of the first packet occurs atthe same time as the end of transmission of the second packet.
 8. Afirst communication device, comprising: a wireless network interfacedevice that is configured to communicate via multiple frequencysegments, the wireless network interface device having one or moreintegrated circuit (IC) devices configured to: determine thatsimultaneous transmission and reception via multiple frequency segmentsis not permitted, control the wireless network interface device totransmit a first packet in a first frequency segment beginning at afirst time, control the wireless network interface device to transmit asecond packet in a second frequency segment beginning at a second timethat is different than the first time, wherein transmission of thesecond packet overlaps in time with transmission of the first packet,and in response to having determined that simultaneous transmission andreception via multiple frequency segments is not permitted, include inthe first packet padding so that an end of transmission of the firstpacket occurs at a same time as an end of transmission of the secondpacket.
 9. The first communication device of claim 8, wherein the one ormore IC devices are configured to: determine that the firstcommunication device is not permitted to simultaneously transmit andreceive via multiple frequency segments.
 10. The first communicationdevice of claim 8, wherein the one or more IC devices are configured to:control the wireless network interface device to transmit the secondpacket to a second communication device in the second frequency segment;and determine that simultaneous transmission and reception via multiplefrequency segments is not permitted at least by determining that thesecond communication device is not permitted to simultaneously transmitand receive via multiple frequency segments.
 11. The first communicationdevice of claim 10, wherein the one or more IC devices are configuredto: determine that the second communication device is not permitted tosimultaneously transmit and receive via multiple frequency segmentsusing information in a third packet, received from the secondcommunication device, the information in the third packet indicatingthat the second communication device is not permitted to simultaneouslytransmit and receive via multiple frequency segments.
 12. The firstcommunication device of claim 8, wherein the one or more IC devices areconfigured to: determine that simultaneous transmission and receptionvia multiple frequency segments is not permitted at least by determiningthat simultaneous transmission and reception via multiple frequencysegments is not permitted in a WLAN to which the communication devicebelongs.
 13. The first communication device of claim 12, wherein the oneor more IC devices are configured to: determine that simultaneoustransmission and reception via multiple frequency segments is notpermitted in the WLAN using information in a third packet, received froman access point that manages the WLAN, the information in the thirdpacket indicating that simultaneous transmission and reception viamultiple frequency segments is not permitted in the WLAN.
 14. The firstcommunication device of claim 8, wherein: the wireless network interfacecomprises a physical layer (PHY) processor implemented on the one ormore IC devices; and the one or more IC devices are configured to, inresponse to determining that simultaneous transmission and reception viamultiple frequency segments is not permitted, prompt the PHY processorto include in the first packet the padding so that the end oftransmission of the first packet occurs at the same time as the end oftransmission of the second packet.
 15. A method for simultaneouslytransmitting in multiple frequency segments, comprising: performing, ata communication device, a backoff operation corresponding to a firstfrequency segment among the multiple frequency segments, the backoffoperation involving decrementing a first backoff counter in connectionwith the first frequency segment; determining, at the communicationdevice, whether the first backoff counter is expired; determining, atthe communication device, whether one or more second backoff counters,decremented in connection with one of more second frequency segments,among the multiple frequency segments, have expired; and in response todetermining that the first backoff counter and the one or more secondbackoff counters have expired, simultaneously transmitting, by thecommunication device, respective transmissions in respective frequencysegments beginning at a same time.
 16. The method of claim 15, furthercomprising: decrementing, by the communication device, the first backoffcounter when a subchannel in the first frequency segment is determinedto be idle; and suspending, by the communication device, thedecrementing of the first backoff counter when the subchannel in thefirst frequency segment is determined to be busy.
 17. The method ofclaim 16, further comprising: in connection with determining that thefirst backoff counter has expired, determining, at the communicationdevice, whether one or more other subchannels in the first frequencysegment are idle for a predetermined time period prior to a beginning ofthe respective transmissions in respective frequency segments; whereinsimultaneously transmitting the respective transmissions in therespective frequency segments beginning at the same time is further inresponse to determining that the one or more other subchannels in thefirst frequency segment are idle for the predetermined time period. 18.The method of claim 17, further comprising: in response to determiningthat one or more other subchannels in the first frequency segment arebusy during the predetermined time period, determining to postpone thesimultaneous transmission of the respective transmissions in therespective frequency segments.
 19. The method of claim 15, wherein, inconnection with a subsequent simultaneous transmission in multiplefrequency segments: selecting, at the communication device, anotherfrequency segment different than the first frequency segment;performing, at the communication device, another backoff operationcorresponding to the other frequency segment different than the firstfrequency segment, the other backoff operation including decrementingthe first backoff counter or a particular second backoff counter, amongthe one or more second backoff counters, in connection with the otherfrequency segment; determining, at the communication device, whether thefirst backoff counter or the particular second backoff counter isexpired; and in response to determining that the first backoff counteror the particular second backoff counter has expired, performing, by thecommunication device, the subsequent simultaneous transmission in themultiple frequency segments.
 20. A communication device, comprising: awireless network interface device that is configured to communicate viamultiple frequency segments, the wireless network interface deviceincluding one or more integrated circuit (IC) devices and a pluralitybackoff counter implemented on the one or more IC devices, wherein theone or more IC devices are configured to: perform a backoff operationcorresponding to a first frequency segment among the multiple frequencysegments, the backoff operation involving decrementing a first backoffcounter among the plurality of backoff counters in connection with thefirst frequency segment, determine whether the first backoff counter isexpired, determine whether one or more second backoff counters, amongthe plurality of backoff counters, decremented in connect with one ormore second frequency segments, among the multiple frequency segments,have expired, and in response to determining that the first backoffcounter and the one or more second backoff counters have expired,control the wireless network interface device to simultaneously transmitrespective transmissions in respective frequency segments, among themultiple frequency segments, beginning at a same time.
 21. Thecommunication device of claim 20, wherein the one or more IC devices arefurther configured to: decrement the first backoff counter when asubchannel in the first frequency segment is determined to be idle; andsuspend the decrementing of the first backoff counter when thesubchannel in the first frequency segment is determined to be busy. 22.The communication device of claim 21, wherein the one or more IC devicesare further configured to: in connection with determining that the firstbackoff counter has expired, determine whether one or more othersubchannels in the first frequency segment are idle for a predeterminedtime period prior to a beginning of the respective transmissions inrespective frequency segments; and control the wireless networkinterface device to simultaneously transmit the respective transmissionsin the respective frequency segments further in response to determiningthat the one or more other subchannels in the first frequency segmentare idle for the predetermined time period.
 23. The communication deviceof claim 22, wherein the one or more IC devices are further configuredto: in response to determining that one or more other subchannels in thefirst frequency segment are busy during the predetermined time period,determine to postpone the simultaneous transmission of the respectivetransmissions in the respective frequency segments.
 24. Thecommunication device of claim 20, wherein the one or more IC devices arefurther configured to, in connection with a subsequent simultaneoustransmission in multiple frequency segments: select another frequencysegment different than the first frequency segment; perform anotherbackoff operation corresponding to the other frequency segment differentthan the one frequency segment, the other backoff operation includingdecrementing the first backoff counter or a particular second backoffcounter, among the one or more second backoff counters, in connectionwith the other frequency segment; determine whether the first backoffcounter or the particular second backoff counter is expired; and inresponse to determining that the first backoff counter or the particularsecond backoff counter has expired, control the wireless networkinterface device to perform the subsequent simultaneous transmission inthe multiple frequency segments.